Gemstone Properties

Gemstone Properties

Name Hardness Specific Gravity Structure Refractive Index Birefringence Plechorism Fluorescence
Agate (Quartz) 6.5+ 2.60-2.65 Hexagonal 1.54-1.55 up to +0.006 None Variable
Alabaster 2+ 2.30-2.33 Microcrystaline 1.520-1.530 0.01
Alexandrite 8.5 3.70-3.73 Orthorhombic 1.744-1.755 0.011 v Weak None
Almandine Garnet 7.5 3.95-4.20 Isometric 1.78-1.81 None None None
Amazonite 6+ 2.56-2.58 Triclinic 1.522-1.530 -0.008 None Weak
Amber 2to3 1.05-1.30 Amorphous 1.54 None None Variable
Amblygonite 6 3.01-3.03 Triclinic 1.611-1.637 0.026 None v Weak
Amethyst Quartz 7 2.63-2.65 Hexagonal 1.544-1.553 0.009 v Weak Weak
Anatase 5.5+ 3.82-3.95
Andalusite 7.5 3.12-3.18 Orthorhombic 1.641-1.648 -0.007 Strong Weak
Andradite Garnet 7+ 3.60-3.68 Isometric 1.738-1.745 None None None
Anhydrite 3+ 2.90-2.99 Orthorhombic
Apatite 5 3.17-3.23 Hexagonal 1.632-1.646 -0.002 -0.004 Weak to v Strong Variable
Apophylite Fish-eye 4.5+ 2.30-2.50 Tetragonal
Aquamarine 7.5+ 2.67-2.71 Hexagonal 1.577-1.583 -0.006 Definite None
Aragonite Tufa Travertine 3.5+ 2.94 1.530-1.685 -0.155
Augelite 5 2.7
Aventurine Feldspar 6+ 2.62-2.65 Triclinic 1.532-1.542 0.01 Weak Dark brown-red
Axinite 6.5+ 3.27-3.29 Triclinic 1.675-1.685 -0.01 Strong None
Azurite 3.5+ 3.7-3.9 Monoclinic 1.730-1.838 0.108 Definite None
Barite Barytes 3 4.5 Orthorhombic
Barytocalcite 4 3.66 Monoclinic
Benitoite 6+ 3.65-3.68 Triagonal 1.757-1.804 0.047 v Strong Strong blue
Beryl 7.5+ 2.65-2.75 Hexagonal 1.570-1.600 -0.006 -0.009 Definite to weak Weak to none
Beryllonite 5.5+ 2.80-2.85 Monoclinic 1.553-1.562 -0.009 None None
Brazilianite 5.5 2.98-2.99 Monoclinic 1.603-1.623 0.02 v Weak None
Bytownite 6 2.71-2.74
Calcite 3 2.71 Hexagonal
Cancrinite 5 to 6 2.4-2.5
Cassiterite 6 to 7 6.8-7.1 Tetragonal 1.997-2.093 0.096 Definite None
Celestine Celestite 3+ 3.97-4.00 Orthorhombic
Cerussite 3.5 6.46-6.57 Orthorhombic 1.804-2.078 -0.274 None Variable to None
Chalcedony (Quartz) 6.5+ 2.58-2.64 Hexagonal 1.544-1.553 upto+0.006 None Blue-white
Chalcopyrite Copperpyrite 3.5+ 4.1-4.3 Tetragonal
Chalybite Siderite 3.5 to 4.5 3.85 Hexagonal
Chloromelanite Jade 6.5+ 3.30-3.36 Monoclinic 1.654-1.667 +0.013toNone None v Weak
Chromite 5.5 4.10-4.90
Chrysoberyl 8.5 3.70-3.72 Orthorhombic 1.744-1.755 0.011 v Weak None
Chrysocolla 2 to 5.5 2.00-2.40 Amorphous About1.50 None Weak None
Chrysoprase (Quartz) 6.5+ 2.58-2.64 Hexagonal 1.544-1.553 up to +0.004 v Weak None
Citrine Quartz 7 2.65 Hexagonal 1.544-1.553 0.009 v Weak None
Colemanite 4.5 2.42 Monoclinic
Coral 3 to 4 2.6-2.7 hexagonal 1.486-1.658 -0.172 None Weak
Cordierite 7+ 2.58-2.66 Orthorhombic 1.53-1.55 -0.008-0.012 v Strong None
Crocoite 2.5+ 5.9-6.1 Monoclinic
Cuprite 3.5+ 5.85-6.15 Isometric
Danburite 7+ 3 Orthorhombic 1.630-1.636 -0.006 Weak Sky Blue
Datolite 5+ 2.90-5.00 Monoclinic
Dematoid Garnet 6.5+ 3.62-3.85 Isometric 1.888-1.889 None None None
Diamond 10 3.47-3.55 Isometric 2.417-2.419 None None Variable
Diopside 5 to 6 3.27-3.31 Monoclinic 1.671-1.726 0.028 Weak Strong dark violet
Dioptase 5 3.28-3.35 Hexagonal 1.664-1.709 0.053 Weak None
Dolomite 3.5 to 4.5 2.85-2.95 Hexagonal
Dumortierite 7 3.26-3.41 orthorhombic 1.686-1.723 -0.037 Strong Weak
Ekanite 6+ 3.28
Elaeolite 5.5+ 2.55-2.65
Emerald 7.5+ 2.67-2.78 Hexagonal 1.576-1.582 0.006 Definite None
Enstatite 5.5 3.26-3.28 Orthorhombic 1.663-1.673 0.01 Definite None
Epidot 6 to 7 3.4 Monoclinic 1.733-1.768 0.035 Strong None
Euclase 7.5 3.1 Monoclinic 1.652-1.672 0.02 v Weak None
Fluorite 4+ 3.18 Isometric 1.434 None None Usually strong blue-violet
Fossilized Wood (Quartz) 6.5+ 2.60-2.65 Hexagonal About1.54 None None None
Gahnite 7.5+ 3.58-3.98
Garnet 7+ 3.60-3.80 Isometric 1.730-1.815 None None None
Garnierite 2.5+ 2.3-2.8 (Organic)
Gaylussite 2.5 1.99 Monoclinic
Glass* 5 3.15-4.20 Amorphous About1.50 None None Variable
Grossular Garnet 7+ 3.60-3.68 Isometric 1.738-1.745 None None None
Hambergite 7.5 2.35 Orthorhombic 1.559-1.631 0.072 None None
Hauynite 5.5+ 2.4 Isometric
Heliotrope Bloodstone (Quartz) 6.5+ 2.6-2.7 Hexagonal 1.54-1.55 up to +0.006 None Variable
Hematite 5.5 to 6.5 4.95-5.16 Hexagonal 2.94-3.22 -0.28 None None
Hemimorphite 5 3.4-3.5 Orhtorhombic 1.614-1.636 0.022 None Weak to None
Hiddenite Spodumene 6 to 7 3.16-3.20 Monoclinic 1.665-1.680 0.015 Definite v Weak
Howlite 3.5 2.53-2.59 Monoclinic
Hypersthene 5 to 6 3.4-3.5 Orthorhombic
Idocrase 6.5 3.32-3.42 Tetragonal 1.700-1.721 +-0.005 Weak None
Ilmenite 5 to 6 4.72
Iolite 7+ 2.58-2.66 Orthorhombic 1.53-1.55 -0.008-0.012 v Strong None
Ivory 2 to 4 1.7-2.0 (Organic) 1.54 None None Various blues
Jadeite Jade 6.5+ 3.35 Monoclinic 1.654-1.667 +0.013 to None None v Weak
Jasper Quartz 6.5+ 2.58-2.91 Hexagonal About1.54 None None None
Jet 2.5 to 4 1.30-1.35 1.64-1.68 None None None
Kornerupine 6.5+ 3.27-3.31 Orthorhombic 1.665-1.682 -0.013 Strong None
Kunzite Spodumene 6 to 7 3.16-3.20 Monoclinic 1.665-1.680 0.015 Definite Strong
Kurnakovite 4.5 1.86 Triclinic
Kyanite 4.5 to 7 3.65-3.69 Triclinic 1.715-1.732 -0.017 Strong blues to colorless Strong red
Labradorite 6+ 2.69-2.70 Triclinic 1.560-1.568 0.008 None Yellow striations
Lapis Lazuli 5 to 6 2.4-2.9 Isometric About 1.50 None None Strong white
Lazulite 5 to 6 3.1-3.2 Monoclinic 1.615-1.673 -0.03 Strong None
Leucite 5.5 2.45-2.50 Isometricand Tetragonal
Magnesite 4 3.0-3.12
Malachite 3.5+ 3.75-3.95 Monoclinic 1.655-1.909 -0.254 v Strong None
Meerschaum 2+ 2 Orthorhombic Microcrystaline 1.53 None None None
Moissanite* 9.5 3.2 Yes
Moldavite (tektite) 5.5 2.32-2.38 Amorphous 1.48-1.50 None None None
Moonstone 6+ 2.56-2.62 Monoclinic 1.520-1.525 -0.005 None Weak
Natrolite 5.5 2.20-2.25 Orthorhombic
Nephrite Jade 6+ 2.90-3.02 Monoclinic 1.600-1.627 -0.027 to none Weak None
Obsidian (Naturalglass) 5+ 2.3-2.8 Amorphous 1.48-1.51 None None None
Opal 5.5 to 6.5 1.98-2.20 Amorphous 1.44-1.46 None None Variable
Orthoclase 6+ 2.56-2.60 Monoclinic 1.520-1.525 -0.005 None Weak
Painite 7.5+ 4.1
Pearl 3 to 4 2.60-2.78 Microcrystaline 1.52-1.69 Weak or none None Weak
Periclase 5.5+ 3.70-3.90 Isometric
Peridot 6.5+ 3.27-3.36 Orthorhombic 1.654-1.690 0.036 v Weak None
Petalite 6+ 2.4 Monoclinic 1.502-1.518 0.016 None Weak orange
Phosgenite 2.5+ 6.13 Tetragonal
Prasiolite** (Quartz) 7 2.65 Hexagonal 1.544-1.553 0.009 v Weak None
Prehnite 6+ 2.87-2.93 Orthorhombic 1.61-1.64 0.03 None None
Proustite Rubysilver 2.5 5.57-5.64 Tetragonal
Pseudophite 2.5 2.5-2.6
Psilomelane 5.5+ 4.35
Purpurite 4.5 3.2-3.4 Orthorhombic
Pyrite 6+ 5.0-5.2 Isometric Over1.81 None None None
Pyrope Garnet 7+ 3.65-3.80 Isometric 1.730-1.760 None None None
Rhodochrosite 4 3.30-3.70 Hexagonal 1.600-1.820 -0.22 None Weak red
Rhodolite (PyropeGarnet) 7+ 3.65-3.80 Isometric 1.730-1.760 None None None
Rhodonite 5.5 to 6.5 3.40-3.70 Triclinic 1.733-1.744 0.011 Definite None
Rhodozite 8 3.4
Rock-Crystal (Quartz) 7 2.65 Hexagonal 1.544-1.553 0.009 v Weak None
Rose Quartz 7 2.65 Hexagonal 1.544-1.553 0.009 Weak Weak
Ruby Corundum 9 3.97-4.08 Hexagonal 1.766-1.774 -0.008 Strong Strong red
Rutile 6+ 4.20-4.30 Tetragonal
Sanidine 6 2.57-2.58
Sapphire Corundum 9 3.99-4.00 Hexagonal 1.766-1.774 -0.008 Varies Variable
SardQuartz 6.5+ 2.58-2.64 Hexagonal 1.544-1.553 up to +0.006 None None
Scapolite 5 to 6.5 2.57-2.74 Tetragonal 1.540-1.560 -0.009 -0.020 Definite Variable
Scheelite 4.5+ 5.1-6.1 Tetragonal 1.918-1.934 0.016 Definite Variable
Serpentine 2.5 2.4-2.8 Monoclinic 1.560-1.571 None None Partly yellow
Sillimanite 6 to 7.5 3.25
Sinhalite 6.5 3.47-3.49 Orthorhombic 1.669-1.707 -0.038 Definite None
Smaragdite 6.5 3.25 Monoclinic
Smithsonite 5 4.3-4.5 Hexagonal 1.621-1.849 -0.228 None None
SmokyQuartz 7 2.65 Hexagonal 1.544-1.553 0.009 Definite None
Sodalite 5.5+ 2.13-2.29 Isometric 1.48 None None Strong orange
Spessartite (Garnet) 7+ 4.12-4.20 Isometric 1.795-1.815 None None None
Sphalerite 3.5+ 4.08-4.10 Cubic 2.368-2.371 None None Variable to None
Sphene 5+ 3.52-5.54 Monoclinic 1.885-2.050 +0.105 +0.135 Variable None
Spinel 8 3.58-3.61 Isometric 1.712-1.736 None None Strong red Weak other colors
Staurolite 7+ 3.7-3.8
Stichtite 1.5 to 2.5 2.2 Monoclinic 1.560-1.571 None None
Strontiumtitanite* 6+ 5.13
Sulphur 1.5+ 2.05-2.08 Orthorhombic
Taaffeite 8 3.6
Tantalite 5 to 6 5.18-8.20 Orthorhombic
Tanzanite 6.5+ 3.28-3.35 Orthorhombic 1.691-1.700 0.009 v Strong None
Thomsonite 5+ 2.3-2.4
Thulite 6 3.35 Orthorhombic 1.691-1.700 0.009 None None
Tiger's Eye (Quartz) 7 2.64-2.71 Hexagonal 1.544-1.553 0.009 None None
Topaz 8 3.53-3.56 Orthorhombic 1.610-1.638 +0.008 -0.010 Definite to weak Weak
Tourmaline 7+ 3.02-3.26 Hexagonal 1.616-1.652 -0.014 -0.044 Definite to strong Weak
Tremolite 5.5 to 6.5 2.90-3.10
Tugtipite 6 2.36-2.57 Tetragonal Strong red
Turquoise 5 to 6 2.60-2.80 Triclinic 1.61-1.65 0.04 Weak Weak
Ulexite 2 1.9-2.0 Triclinic 1.491-1.520 0.029 None variable
Uvarovite Garnet 7.5 3.77 Isometric 1.87 None None None
Variscite 4 to 5 2.4-2.6 Orthorhombic 1.55-1.59 -0.01 None None
Vivianite 1.5 to 3 2.6-2.7 Monoclinic
Wardite 5 2.81
Willemite 5.5 3.89-4.18 Tetragonal Strong green
Witherite 3.5 4.27-4.35 Orthorhombic
Wulfenite 3 6.7-7.0 Tetragonal
YAG* 8 4.6
Zincite 4.5+ 5.66 Hexagonal
Zircon 6.5 to 7.5 4.90-4.71 Tetragonal 1.777-1.987 0.059 v WeaktoDefinite Weak
Zoisite 6.5+ 3.28-3.35 Orthorhombic 1.691-1.700 0.009 v Strong None